The present application is directed to devices to mount with the sacrum, and more specifically to devices that attach to the sacrum and provide a support for positioning an implant between the sacrum and fifth lumbar vertebra.
The spine is divided into regions that include the cervical, thoracic, lumbar, and sacrococcygeal regions. The cervical region includes the top seven vertebrae identified as C1-C7. The thoracic region includes the next twelve vertebrae identified as T1-T12. The lumbar region includes five vertebrae L1-L5. The sacrococcygeal region includes nine fused vertebrae comprising the sacrum comprising S1-S5 vertebrae and four or five rudimentary members that form the coccyx.
The sacrum is shaped like an inverted triangle with the base at the top. The sacrum acts as a wedge between the two iliac bones of the pelvis and transmits the axial loading forces of the spine to the pelvis and lower extremities. The sacrum is rotated anteriorly with the superior endplate of the S1 vertebra angled from about 30 to about 60 degrees in the horizontal plane.
The S1 vertebra includes a spinous process aligned along a ridge called the medial sacral crest. However, the spinous process on the S1 vertebra may not be well defined and therefore not adequate for supporting an implant. One example of this dilemma is the inability of the spinous process to adequately support an interspinous process implant positioned between the L5 and S1 spinous processes.